So far, derivatives of 2-phenyl-3-hydroxyquinoline-4(1H)-one referred to in the present invention have not been described in literature. Derivatives of 2-phenyl-3-hydroxyquinoline-4(1H)-one of the general formula I have been described in the literature
as well as some other of its derivatives, which are substituted by various substituents.
A derivative substituted by chlorine atom in the position 6 of the quinolone skeleton has been described in the paper by Spence et al. (J. Chem. Soc., 1971, 3712-3719.). Preparation of this derivative is further described, which is based on o-nitrobenzaldehyde (1), which upon reaction with bromacetonphenon using the Darzens reaction yields trans-1-benzoyl-2-(o-nitrophenyl)ethylene epoxide (2), which under the activity of hydrogen chloride gives rise to 6-chlorine-1,3-dihydroxy-2-phenylquinoline-4(1H)-one (3), which upon subsequent reduction by dithionite yields 6-chlorine-2-phenyl-3-hydroxyquinoline-4(1H)-one (4), as shown in the Scheme 1.

Sui et al. (Eur. J. Med. Chem., 1999, 34, 381.) described preparation of substituted derivatives containing hydroxy group in the position 5 and 7 and a combination of substituents of e.g. hydrogen atom, halogen atom or trifluormethyl group or hydroxy group in the position 3′, 4′ and 5′. These derivatives are inhibitors of procaryotic topoisomerase II and DNA gyrase. Preparation of these derivatives is based on substituted aniline (5), which yields a ketone (6) by Susagawa's acylation with suitable acetonitrile. Ring closure to 3-methoxy-4quinolones (7) is achieved upon subsequent N-acylation by benzoylchloride and under subsequent activity of sodium methanolate. Derivatives of quinolone (8) shown in the Scheme 2 are produced upon subsequent demethylation by hydrogen bromide.

Hradil et al. (Collect. Czech. Chem. Commun., 1995, 60, 1357) described preparation of derivatives containing combinations of substituents such as hydrogen atoms, halogen atoms, nitro- or amino groups or amino groups substituted by isopropyl in the position 2′, 3′, 4′ and 5′. Preparation of these derivatives is based on a suitable substituted salt of anthranilic acid (9), which upon reaction with bromacetonphenon yields phenacyl esters (10), which yield quinolone derivatives (11) upon ring closure with polyphosphoric acid—(Scheme 3).
